The prior art describes that 1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol, also known under the name of ethyl-tetrahydroionol, possesses useful odorous properties, namely as a fixative [see DE-AS No. 28 07 584]. By trying to reproduce the process disclosed in said document however, we discovered that the product obtained was in fact constituted by a mixture eminently consisting of cis-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol accompanied by a minor amount, of the order of about 10 to 12%, of the trans isomer.
The prior art process is illustrated by the following reaction pathway: ##STR2##
DE-AS No. 28 07 584 is mute however as to the isomeric nature of the product obtained by said process. By way of consequence, it fails to recognize any distinctive character of the odor shown by the individual discreet isomers.
We have discovered surprisingly that trans-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol not only is a useful perfuming ingredient in its own right, but that its properties are distinct from those of the cis isomer and its power far superior to that shown by this latter compound. For simplicity's sake, the product described in DE-AS No. 28 07 584 will be referred to in the following description by its commercial name, TIMBEROL (origin: Dragoco, Holzminden, FRG).
Thanks to the process of the instant invention, it is now possible to prepare a product eminently consisting of trans-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol or of a composition consisting of from less than 100% to more than about 80% of trans-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol and a definite amount, but not more than about 20% of cis-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol. The difference observed between the odor of these two isomers underlines once again the unpredictability of the phenomenon of odor perception. In effect, though both these compounds develop a scent of woody and ambery type, the trans isomer, and the mixtures thereof containing major amount of it, show a more pronounced animal and ambery character. Its animal note can be defined as being almost faecal. The composition of the invention shows moreover a woody character reminiscent of vetyver oil, whereas TIMBEROL develops a woodiness related to cedar wood or patchouli essential oil.
The difference between the two compounds is even more pronounced with respect to their odor strength. We have discovered that the composition of the invention is remarkably more powerful than TIMBEROL. Evaluated on a paper sniffing strip, it could be established that an alcoholic solution at 5% (by weight in 95% ethanol) of the composition of the invention possesses an odor strength similar to that shown by pure TIMBEROL: its power is therefore about twenty times higher than that of the known commercial compound.
The evaluations of the odor threshold values we have carried out on aqueous solutions, according to Guadagni et al. [J. Amer. Food Agric. 14, 761 (1963)], have indicated a value of 32 ppb (parts per billion) for trans-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol and 240 ppb for its cis isomer. The chemical purity of the tested compounds was .gtoreq.99% and .gtoreq.99.5%, respectively.
Concerning the substantivity of these compounds on textile materials, we could observe that both the composition of the invention and the prior art compound possess an excellent substantivity on fabrics subjected to washing and treatment with liquid and solid detergents, and with fabric softeners of various nature, irrespective of whether they were anionic, cationic or non ionic. However, the degree of substantivity of trans-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol is higher than that of its cis isomer.
Owing to its properties, trans-1-(2,6,6-trimethylcyclohexyl)-hexan-3-ol and mixtures thereof containing major amount of it possess clear advantages over the prior art compound and consequently their utilization in perfume compositions and perfumed products favorably enlarges the degree of perfumer's creativity.